Foot orthotics are often used to compensate for impaired foot function by controlling abnormal motion across the joints of the foot. Specific impairments that a foot orthotic may assist include mild “foot drop” due to neurological conditions, orthopedic gait abnormality, clubfoot, mid-tarsal fracture, partial foot amputation, arthritis, hallux valgus, hallux rigidus, turf toe, and plantar fasciitis. Foot orthotics may also be prescribed to reduce pain, to provide support, to prevent foot deformity or prevent the worsening thereof, to relieve pressure on a certain area of the foot, and to improve the overall biomechanical function of the foot and lower extremity limbs.
In their basic form, functional foot orthotics or orthotic footplates work like shock absorbers, removing pressure and stress from painful areas of the foot and ankle while controlling abnormal position and movement of the foot. Moreover, they promote the proper alignment of the feet and can restore balance. Orthotic footplates operate to hold the heel and middle portion of a foot in a more stable position when a person is walking or standing, and thus allow the foot to function more efficiently during weight-bearing and propulsion.
Known orthotic footplates tend to have an equal stiffness along their length. It has been found, however, that a footplate having equal stiffness may further contribute to an abnormal gait by overcompensating a foot at a toe portion. More specifically, during toe-off of a gait cycle, the toe portion has a tendency to bend around the largest moment of the footplate. This, in turn, results in a considerable amount of pressure being placed on the plantar surface of the foot. Hence, these orthotic footplates may actually worsens a condition and create orthopedic problems elsewhere in the body.
Accordingly, it is desirable to provide an orthotic footplate that has a stiffness gradient that corresponds to ground reaction forces as they are applied to a foot and released by a foot during a swing phase of a gait cycle, while providing the necessary support and shock absorption to a foot during a stance phase of a gait cycle.
In addition to foot impairment, an ankle-foot orthosis is often prescribed for users having gait deviations that relate to muscle weakness. An ankle-foot orthosis substitutes or compensates for weak dorsiflexors during the swing phase and for weak plantarflexors during the stance phase of a user's gait. In effect, an ankle-foot orthosis can be used to support and align the ankle and the foot, suppress spastic and overpowering ankle and foot muscles, to assist weak and paralyzed muscles of the ankle and foot, to prevent and correct ankle and foot deformities, and to improve the functions of the foot.
Many known ankle-foot orthoses are configured to concentrate on the ankle and knee biomechanics while only providing minimal support to the foot. It has been found, however, that users of ankle-foot orthoses require at least some foot support of the type offered by the aforementioned orthotic footplates.
Accordingly, it is desirable to provide an ankle-foot orthosis having an orthotic footplate that improves biomechanical function of the foot, ankle and knee. Furthermore, it is desirable to provide an ankle-foot orthosis imparting improved stability of a foot and leg over conventional ankle-foot orthoses while maintaining a lightweight structure that comfortably secures to a user's foot while providing suitable support.